There is no shortage of online carbon calculators these days. They're all the rage with pressure groups and governments - in fact a new one seems to be launched almost every week.

The latest to enter the fray is the British Government with their "official" Act On C02 tool. (Don't bother trying to use it if you don't live in the UK though - it only works if you have a British postcode).

Work through a long series of multiple choice questions and eventually you're presented with a figure that purports to be an estimate of the amount of carbon emissions for which you are responsible.

The Defra calculator, however, has not been without controversy. Friends of the Earth gave it a lukewarm response, while Greenpeace damned the initiative as a "gimmick" that was diverting attention away from the important issues of climate change.

The other problem with carbon calculators generally is that they rarely agree with each other because there is no international standard for calculating emissions.This is especially the case when it comes to aviation emisisons where, it seems, no one can agree on how bad flying is for the environment.

Ultimately, however, arguing over the exact amount of an individual's emssions is a pretty pointless exercise.

Michael Molitor, an expert on calculating and mitigating emissions who heads up a mob called CarbonShift, reckons figuring out your emissions just takes a bit of common sense and that calculators should be approached with caution.

"Be smart," he says. "The average Australian emits 28 tonnes and that includes newborn babies sitting in their hampers and 93-year-old ladies sitting nursing homes who aren't emitting a whole lot of carbon.

"If you are 26 and have a job in the CBD you ain't emitting 28 tonnes you are emitting more. So if you get on a site and and it calculates you are emitting 300 tonnes and you're not flying 300,000km a year, it's wong and if it says you emit two tonnes a year then it's also wrong."

Molitor says a reliable estimate for 95 per cent of Australians is around 30 tonnes a year.

The important thing it seems is not to get too hung up on measuring every last gram of carbon but to get on and do something about reducing it.

How you calculated your emissions? Do you have much faith in online calculators or do you reckon they are all a big waste of time?

Of late, I've been particularly struck by these "green blues" (loosely defined as an amalgamation of helplessness and anger, generally brought on by the greed and stupidity of politicians and business leaders who just don't get it).

My own personal antidote to the green blues is to get my hands dirty in the garden.

It's no secret among gardeners that growing stuff is enormously therapeutic - and there is nothing more therapeutic or satisfying, I reckon, than growing some of your own food.

In the Years BC (before children) we had a substantial veggie patch - about 20 square metres. And in spite of sharing the produce with cockatoos, possums, bandicoots and other marauding local wildlife (including feral deer), we did pretty well for a few seasons.

Then kids came along, our energies were redirected and the veggie patch became a mass of weeds and, ultimately, was returned to lawn.

But since then I've really missed that connection with the natural world that comes from growing a little food and recently we have reclaimed a small part of the yard from the chooks and returned it to food production.

The beauty now is also that the kids are old enough to take part in planting and weeding - and eating the results. They are about to start their own personal veggie patches too, which is firing their imagination enormously.

As an overall proportion of our diet, the home-grown stuff is pretty minimal, but at least my kids now know that beans don't start out in cans.

It's just a huge shame that, thanks to "progress", most of us have lost the habit of growing at least some of our own food. And while I know producing your own broccoli or rocket is hardly going to save the world, it's still one of the most important ways we have of keeping in touch with that abstract entity called "the environment".

Do you grow any of your own food, or is it all too much bother when there's a supermarket around the corner?

The sudden speed with which the environment in general and climate change in particular has come to dominate the public debate is nothing short of startling.

If you'd predicted two years ago that green issues would be front and centre at this year's federal election you would have been met with derision.

Likewise, the idea of an "eco-pack" of Holywood celebs like George Clooney, Brad Pitt and Julia Roberts becoming almost as well known for their green pronouncements as their movies would have been unthinkable in the recent past.

Meanwhile, recycling, water tanks and solar power ahave gone from being fringe interests to become solidly mainstream.

The environment has never been more fashionable, topical or trendy (which must be a little galling to those eco-warhorses who spent a lifetime banging on about it to little or no avail).

And personally, I am rapt that governments and business are finally, if reluctantly, beginning to focus on what really matters.

However, call me a pessimist if you will (and, frankly, I've been called much worse) but I can't help but feel a slight sense of foreboding.

What happens when the environment and sustainable living stop being trendy? What happens when the green equivalent of "donor fatigue" settles in and everyone moves on?

And what happens if our governments detect that we have had our "green moment" and just as quickly lost our enthusiasm again? What if if this is not a turning point but merely another passing fad for the vast majority of people?

I'm not saying that this is what will happen, just that it's a risk. In this piece in today's paper, Tim Elliott takes aim at the air of smugness that can be detected hanging over some born-again greenies.

If that perception of smugness becomes widespread, perhaps a serious anti-green backlash is only around the corner - a response plenty of vested interests would be only too happy to encourage.

Am I worrying unnecessarily? Are we living through a historic period that we will look back upon as the point at which western civilisation saved itself? Or will this new-found eco-consciousness merely turn out to be a passing phase as we continue on our inevitable path to self-destruction?

Sometimes the biggest, most important questions get overlooked because at first glance they appear too simplistic to bother with.

Here's one that couldn't be more basic: are you happy?

It sounds like the sort of thing a child might ask (or even worse, a chapter heading in a self-help book).

But asking this naive little question has the potential to go right to the heart of how we relate to the natural environment.

In most western nations the overall level of happiness has barely increased since the Second World War - but this is during a period when we have seen unprecedented increases in per capita income.

There are also plenty of studies around showing that, beyond a certain level, these is little relationship between income and happiness.

Put all that together with the fact that the same economic growth that has delivered material wealth to a proportion of the world's population has brought about dangerous climate change and you (or at least, I) arrive at a pretty confronting question: "If accelerating economic growth is not making us on average any happier while at the same time stuffing up the planet big time, then how stupid does that make us?"

This is roughly the thesis advanced (far more elegantly) by Tony Juniper, one of the bosses of Friends of the Earth International, in this piece taken from his thought-provoking book "How Many Lightbulbs Does it Take to Change a Planet" .

Juniper doesn't say all growth is bad, just that we need to "be more careful about what we are measuring as growth". A similar argument is advanced by economist Richard Douthwaite in this essay from 1997.

Obviously, it's not a point of view you're likely to hear discussed in mainstream political debate any time soon, which is a shame, because it seems to merit much closer examination.